RSTP (IEEE 802.1w) is an evolution of the original 802.1D standard and is incorporated into the IEEE 802.1D-2004 standard. The 802.1w STP terminology remains primarily the same as the original IEEE 802.1D STP terminology. Most parameters have been left unchanged, so users familiar with STP can easily configure the new protocol. Rapid PVST+ is simply the Cisco implementation of RSTP on a per-VLAN basis. With Rapid PVST+, an independent instance of RSTP runs for each VLAN.

The figure shows a network running RSTP. S1 is the root bridge with two designated ports in a forwarding state. RSTP supports a new port type: port F0/3 on S2 is an alternate port in discarding state. Notice that there are no blocking ports. RSTP does not have a blocking port state. RSTP defines port states as discarding, learning, or forwarding.

RSTP speeds the recalculation of the spanning tree when the Layer 2 network topology changes. RSTP can achieve much faster convergence in a properly configured network, sometimes in as little as a few hundred milliseconds. RSTP redefines the type of ports and their state. If a port is configured to be an alternate port or a backup port, it can immediately change to forwarding state without waiting for the network to converge. The following briefly describes RSTP characteristics: